Method of manufacturing molds, dies or forming tools having a cavity formed by thermal spraying

ABSTRACT

Described are molds, dies and forming tools comprising: a) a heat exchanging body support member; and b) within the support member, a molding cavity portion formed by thermal spraying metallic particles to a desired configuration in the support member. Also described are methods of making a mold, die or forming tool comprising the steps of: a) providing a body support member having a controlled and designed porosity which permits the enhancement of the heat transfer ability of said mold, die or forming tool; b) configuring a surface of the support member to a desired cavity; and c) spraying particles to the configured cavity in the support member, thereby producing a mold, die or forming tool. Preferably, the materials of construction are metallic and are applied by thermal plasma spraying. The particles may also be ceramics, metal matrix composites, ceramic matrix composites, thermoplastic resins, thermoset resins, and composites based thereupon. The controlled porosity of the body of the mold, die and/or forming tool is as important as the use of thermal spray to subsequently form the cavity.

TECHNICAL FIELD

The present invention relates to the fields of molds, dies, and otherforming tools, their manufacture and their use in metal manufacturingand plastic manufacturing.

BACKGROUND ART

Molds are generally metallic and are comprised of a body portion and acavity portion. A key feature to increased productivity for moldingoperations is to dissipate the heat that is generated during the moldingprocess. In other words, the faster one can dissipate the heat in themolding operation, the faster one can increase the cycle time formolding.

Molding is used as a technique for fabricating metallic articles such asin a shaping process. Molding is also used for the formation ofthermoplastic and thermoset, as well as elastomeric materials which aregenerally characterized as plastic materials.

Thermal spraying is generally characterized as a group of processes inwhich finely divided metallic or non-metallic surfacing materials aredeposited in a molten or semi-molten condition on a prepared substrateto form a spray deposit. "Thermal spraying" is a term generally appliedto such other processes called arc spraying, flame spraying, and plasmaspraying. The thermal spraying gun generates the necessary heat by usingcombustible gases or an electric arc. As the materials are heated, theychange to a plastic or molten state and are accelerated by a compressedgas. The confined stream of particles are conveyed to the substrate. Theparticles strike the surface, flatten and form thin platelets (splats)that conform and adhere to the irregularities of the prepared surfaceand to each other. As the sprayed particles impinge upon the substrate,they cool and build-up, particle by particle, into a lamellar structure,thus a coating is formed. See "Thermal Spraying", Practice, Theory andApplication, published by the American Welding Society, Inc. of Miami,Fla. (1995).

Plasma spraying is a thermal spraying process in which a non-transferredarc is utilized as the source of heat that ionizes a gas which melts andpropels the coating material to the workpiece.

Flame spraying is a thermal spraying process in which an oxyfuel gasflame is the source of heat for melting the surfacing material.Compressed gas may or may not be used for atomizing and propelling thesurfacing material to the substrate.

Arc spraying is a thermal spraying process utilizing an arc between twoconsumable electrodes of surfacing materials as a heat source and acompressed gas to atomize and propel the surfacing material to thesubstrate.

U.S. Pat. No. 3,429,962 discloses a thermal spray technique of forming ametallic oxide article. A rotatable mandrel 15 of, for example, copperor aluminum, has applied thereto a metallic oxide. The final product isobtained by chemically etching away the copper or aluminum mandrel. Theend product is utilized as a fuel cell electrode. In a similar fashion,U.S. Pat. No. 5,006,321 pertains to the thermal spray method ofproducing glass mold plungers.

U.S. Pat. No. 4,460,529 describes the process of manufacturing a ceramichollow body by the thermal spray technique. The ceramic bodies arecomprised of aluminum and titanium carbides, borides, nitrides andmixtures thereof. The appropriate core material is selected so that itwill not bind with the ceramic material. The reference indicates thatthe detachability of a mold core from the hollow body can be assured bythe choice of a core with a higher coefficient of expansion relative tothat of a ceramic or ceramic oxide layer.

U.S. Pat. No. 2,968,083 describes a hot patching of refractorystructures utilizing a spraying of metal.

Other patents of interest include U.S. Pat. Nos. 5,290,373; 4,966,220;5,000,244; 4,482,513; 4,304,747; 4,242,074; 4,547,415; 4,460,529;3,916,418; 4,006,633; and 3,609,829.

It has been stated that spray deposits utilizing thermal spraying do notadd strength to the substrate. Thermal spraying, supra at page 16. Thepresent application, however, does utilize a body that can be cooledvery quickly and the use of thermal spraying onto the body in formingthe cavity of the mold allows for the design of a mold which will haveextremely high strength to permit molding of plastic as well as metallicarticles.

It is an object of the present invention to describe a mold or diehaving a body portion and a cavity portion wherein the cavity portion isformed in the body portion by means of a thermal spraying technique.

It is another object of the present invention to describe themanufacture of molds or dies having a body portion and a cavity portionwherein the cavity portion is formed by a thermal spraying technique.

It is a further object of the present invention to describe themanufacture of plastic or metallic parts by molding the desiredmaterials in a mold that has a body portion and a cavity portion whereinthe cavity portion is formed by thermal spraying metallic particles intothe body portion.

It is a further object of the invention to describe a body portion ofthe invention which permits very high cooling rates and high flexibilityin formation of a cooling means for the body.

SUMMARY OF THE INVENTION

Described is a mold or die comprising: (a) a heat exchanging bodysupport member; and (b) within the support member, a molding cavityportion formed by thermal spraying particles to a desired configurationin the support member. Preferably, the particles are metal or a highmelting temperature plastic.

Also described is a method of making a mold or die comprising the stepsof: (a) providing a heat exchanging body support member; (b) configuringa surface of the support member to a desired cavity; and (c) thermalspraying metallic particles to the configured cavity in the supportmember, thereby producing a mold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the mold or die of the present invention;

FIG. 2 is a cross-section of the mold or die of the present inventiontaken along lines 2--2 of FIG. 1;

FIG. 3 is a schematic process describing the manufacture of the mold ordie of the present invention; and

FIGS. 4 and 5 show a schematic process for molding and releasing aplastic product.

DESCRIPTION OF PREFERRED EMBODIMENTS

In the present application, the invention is broadly related to molds,dies, and other forming tools. The technology applies to tools that areused for the manufacture of parts based on thermoplastic resins,thermoset resins plus glass, metals and alloys.

For metals, molds means tools used for casting only. Dies are used foreither forming or casting. One is able to produce dies and molds for thecasting (such as die casting) and for the forming of metals (such aspressing a sheet or billet into a shape).

For glass part fabrication, molds and dies are used to which thistechnology is applicable. For parts based on thermoplastic resins, theprimary processes are referred to as molding processes, i.e. compressionmolding, transfer molding, blow molding, injection molding, rotomolding,and thermoforming. In addition, dies are used. These include stampingdies. Moreover, extrusion dies are used for the fabrication ofthermoplastic resin-based parts, i.e. film, sheet and profiles, e.g.tubes, rods and detailed shapes. This technology applies to all of thesetypes of tools.

For parts based on thermoset resins, the processes utilize die formingof the part, such as, sheet pressed in dies to form a part followed bycross-linking to achieve strength and related properties. In addition,one has molds such as for the fabrication of urethane foam seating andthe like. This technology applies to the manufacture of all suchtooling.

There are also special part fabrication processes such as pultrusion,filament winding, structural reaction, injection molding, and resintransfer molding. In these processes, one may use a mold or die. Thistechnology applies to the fabrication of such tooling.

In all these cases noted above, heat transfer efficiency and thermalcontrol are key to the product quality and manufacturing economics ofthe parts made from the tools. Further, the manufacturing cost and turnaround time of the mold, die or forming tool in all these cases ispositively impacted.

This technology is universal in its applicability to the forming toolsand to the parts made from thermoplastic resins, thermoset resins, glassmetal, and alloy parts.

The use of the mold of the present invention allows for the formation ofa body portion which can be very easily and rapidly cooled. The reasonfor such a rapid cooling body portion is that the cavity portion of amold is applied to the body portion by use of a thermal sprayingtechnique. Preferably, the thermal spraying is applied directly onto asubstrate such as that formed in the body of a metallic portion.

The invention can also be characterized as the utilization of a bodyportion formed with controlled porosity. The body portion is preferablycomprised of a foam metallic material such as foamed aluminum oraluminum alloys, or other metallic substances that can be readilyfoamed. Such foamed aluminum alloy is available commercially from AlcanAluminum of Canada, or ERG of California.

The body portion may also be comprised of other metallic substances suchas screen or mesh substances. The mesh that can be utilized is one thatwould have varying sizes of an orifice which would permit, as rapid aspossible, flow of coolant of the cavity portion of the mold, yet at thesame time, having sufficient strength to be used in a molding operation.

The body portion may also be comprised of other metallic substances. Onesuch substance is called "tower packing materials". This line ofproducts is used frequently in the petro-chemical industry to createsurfaces for cracking condensation and heat transfer. Structuredpackings are available from Nutter Engineering, a unit ofPatterson-Kelly Company, Division of Harsco Corporation of Tulsa, Okla.Such packing materials are called "Montz B1" or "A3" and the like. Thereare other such materials called "Nutter Ring Random Packing" from NutterEngineering. The Nutter Ring is characterized by having an openhalf-ring with perforated center trough, flanged sides, and two taperedspacing hoops of different diameters. Other packing materials that canbe utilized are called "Intalox™ High Performance Structured Packing"from Norton Chemical Process Products of Akron, Ohio. (Intalox™ is atrademark of Norton Chemical Process Products.) The Intalox™ systemlikewise has Snowflakes™ high performance packing which includes doublecorrugated sheet construction of various metals such as copper and thelike. Also, Raschig rings provided by Norton Chemical Process Productscan equally be applicable as well as Hy-pack Metal Packing or Metal PallRings. Other packing materials supplied by Norton are called "Flexipac"which utilizes a number of the aforementioned materials for structuredpacking. Other materials may likewise be utilized, such as "KochFlexigrid" (trademark of Koch) for structured packing materials or"Flexitray" (trademark of Koch) for valve trays or "Flexiring" (dumpedpacking).

It is to be appreciated, with respect to all of the materials that havea configuration that is open and porous, that the materials would needto be configured or pressed or crushed to a desired size so that asurface can be adequately prepared for the application of the thermalspraying process.

Another material that may be utilized for the body of the mold componentof the present invention is a sintered metal felt. The material isavailable to the trade under the trademark, Feltmetal™ (trademark ofTechnetics Corporation of Deland, Fla.). The fiber metal materials aresintered and are random metal fiber structures produced in the form ofporous sheets. The materials offer a combination of metallic propertiesand make fiber materials suitable for a variety of support applications.The alloys that make up the fiber metal can be iron, chromium, aluminum,yttrium, stainless steel, nickel chromium alloys, nickel, copper, andtitanium and alloy thereof. The material generally has a high porosityof 75%-95% per volume. The fiber metal materials are permeable with upto 0.05 m² /gm of active surface area. The stainless steel materialsmay, for example, have a density of 10% where the nickel metal fiber mayhave a 16% density. A suitable material may be TC3100 which is a nickelfiber that has a surface area of 4,000 square centimeters of surface percc of metal volume. The thermal conductivity of the fiber metalmaterials can be described below in Table I.

                  TABLE I                                                         ______________________________________                                        Thermal Conductivity of Fiber Metal Materials                                                               K                                               Fiber Metal                                                                             Density  Thickness  BTU/hr/                                                                              K                                        Materials %        Inches     ft/°F.                                                                        % Solid                                  ______________________________________                                        Nickel     5       0.25       0.13   0.36                                     Nickel    17       0.50       0.36   1.0                                      Stainless 46       1.00       0.28   3.0                                      Steel                                                                         ______________________________________                                    

For comparison, the thermal conductivity of solid nickel is 36.0KBTU/hr/ft/°F. while 302 stainless steel is 9.4. Air is 0.014 for itsthermal conductivity (data derived from Technetics Corporation DataBulletin for TD-882 fiber metal materials). The fiber metal material isdesirable due to its high porosity and therefore ease of cooling andease of configuring for placement of cooling conduits. The fiber metaloffers formability, weldability, resistance to shock and vibration, andload bearing capability in both tension and compression.

While applicant has described a variety of lightweight molds that may beproduced using the various metallic substrates, it is to be appreciatedthat the invention is broadly directed towards tools. In other words,the invention is directed to dies and other tooling that are light inweight. Most tooling in the past has been extraordinarily heavy becausethe main portion of the tooling is a dense metallic body. Applicant hasfound by the combination of the thermal spraying that one can have abody which is extremely light in weight which would facilitate coolingof the tooling. By having such lightweight body materials, the toolingor die or mold can be readily configured to a variety of shapes in acheaper and easier manufacturing of same.

In general, the materials for construction for the body portion can becharacterized as a foam, a screen, a felt, tubing, honeycomb sinteredspheres or packing tower material, and the like in order to have acontrolled porosity.

The technique of this invention can be used to upgrade cheap materials,e.g. thermal spray cast iron substrates.

The molds or dies are preferably comprised of aluminum and its alloys,iron and its alloys, e.g. cast iron or nickel and its alloys, e.g.,stainless steel.

In the thermal spraying process, any one of a number of commerciallyavailable pieces equipment can be utilized. Reference can be made to thepublication "Thermal Spraying", supra, of the American Welding Society,in particular, chapter 2. The chapter describes typical wire flamespraying, powder flame spray process, an oxygen fuel gas detonation gun,an arc spray gun, a plasma torch which is part of a plasma spray system.All of the equipment is commercially available.

A wide variety of materials can be thermal sprayed onto the body formingthe cavity of the mold. Suitable materials include metals, metallicoxides, metallic carbides, and metallic nitrides. The metals (oxides,carbides or nitrides) may be Groups 2, through and including 8, of thePeriodic Table of Elements. In particular, the metal or metal oxides,metal carbides, or metal nitrides may be aluminum, titanium, silicon,iron, nickel, chrome, zinc, zirconium, calcium, yttrium, magnesium,copper, manganese, molybdenum, tin, antimony, lead, tungsten, boron, andmixtures thereof. In particular, ceramic oxide containing materials maybe used such as blends of aluminum, titanium, silicon, iron oxides, andthe like. Other preferred materials would be iron-based alloys such asthose containing manganese, copper and iron; molybdenum, carbon andiron; chromium, nickel, molybdenum, silicon, carbon and iron, and thelike. Other preferred metallic materials that could be applied by thethermal spray process would be nickel-based materials, namely, thosethat contain measurable amounts of nickel such as that from 10% on up to100% by weight of nickel including various alloys thereof includingaluminum nickel alloys; chromium, nickel alloys; chromium, aluminum,molybdenum, silicon, iron, boron, nickel alloys; nickel, iron, chrome,manganese and molybdenum alloys such as stainless steel, and the like.Other materials would be non-ferrous materials such as copper alloyscontaining aluminum and iron; aluminum alloys containing silicon; highcopper alloys containing substantial amounts of copper such as thatcontaining nickel and copper with or without indium; zinc alloys, andcopper zinc alloys; copper tin alloys; copper, silicon carbide alloys;zinc tin alloys; tin, antimony, copper alloys; tin itself; lead itself;lead tin alloys, and the like. Other materials that may likewise beapplied are carbide alloys such as chromium carbide, nickel and chromiumalloys; tungsten carbide and cobalt alloys; tungsten carbide and nickelalloys; titanium carbide and cobalt or nickel alloys; tungsten carbideand nickel, chromium, boron alloys, and the like.

Other materials that may be applied are refractory metals such astungsten, titanium, molybdenum, or alloys thereof. In addition,self-fluxing alloys may be utilized as a material to be applied in athermal spraying process such as nickel alloys containing chromium,boron, iron, silicon, and carbon, nickel, tungsten carbide, cobalt,chromium, iron, silicon, boron, and carbon alloys; tungsten carbide,cobalt, nickel, chromium, boron, iron, silicon and carbon, and the like.

Other materials that could be applied are tungsten carbides such asthose that contain alloying amounts of cobalt and iron or tungstencarbide with cobalt by itself or tungsten containing substantial amountsof nickel, carbon, chromium, and the like.

Additional materials that may be applied are abradable coatings such asthose contain boron nitride plus nickel alloy materials; nickel plusgraphite composites; silicon, aluminum graphite composites; aluminumplus a polyester material; silicon, aluminum, polyimide material;aluminum, bronze plus boron carbide cermet material; nickel plus agraphite composite material, and the like.

A preferred class of materials that would applied would be the nickelaluminum alloys, in particular, nickel aluminide. It is most preferredthat the material that is to be applied as the cavity to the body wouldbe one that has a very high thermal conductivity. Listed in Table IIbelow are materials that may be used because of their preferred thermalconductivity where the left hand margin indicates watts per thousanddegree Kelvin as the thermal conductivity measurement.

                  TABLE II                                                        ______________________________________                                        Thermally Conductive Materials Of Intrest                                     WATTS/METER K°                                                                       MATERIAL                                                        ______________________________________                                        400           Silver (Pure)                                                                 Copper (Pure)                                                                 Cu/B.sub.4 C                                                                  Gold                                                            300           Cu/Ww                                                                         Al/SiCw                                                                       Aluminum (Pure)                                                               Cu/NI                                                           200           Phosphor Bronze                                                               Beryllium (Pure)                                                              Titanium (Pure)                                                               AIN                                                                           Magnesium                                                                     Tungsten                                                                      SiC                                                                           Al/SiCw                                                                       Molybdenum                                                                    Cu/Ni/Si                                                                      NiAl (Composite) Duplex                                                       Aluminum, Mold Alloys                                                         TiB.sub.2                                                       100           CuBe                                                                          Cobalt, Nickel, Chromium                                                      WC/Co                                                                         Iron                                                                          Cu/Al/Fe                                                                      Steel                                                                         Tool Steel                                                                    Stainless                                                                     Stellite                                                                      (cobalt chromium tungsten alloys)                               ______________________________________                                    

If the thermal spraying process utilizes wire which is heated and passedalong through a gun apparatus, the wire would be comprised of thedesired metallic component and sprayed onto the substrate.

It is to be appreciated that the spraying could take place in variousatmospheres such as an atmosphere containing oxygen, nitrogen, and otherreactive gases or non-reactive gases. The gases may react with themetallic material as it is sprayed or after it is in a molten state onthe substrate. The resulting coating may have different portions of thegas/metal mixture as a portion of the cavities, by virtue of thespraying process in a desirable atmosphere. Preferably, however, theatmosphere is ambient air atmosphere which is a combination of oxygenand nitrogen.

The coating thickness that is to be applied can range from 0.1millimeters to 50 millimeters, preferably, 0.5 to 20 millimeters, andeven more preferably, 0.5 to about 5 millimeters.

It is to be appreciated that one may vary the thermal spraying materialsbased upon the end use of the mold. It may be desirable to have a firstlayer of a thermal spraying process which would be an anchoring layerwith the substrate. A more durable or a higher strength material couldthen be applied onto the initial layer. Therefore, multiple layers maybe applied to the body of the mold to achieve a cavity having acombination of properties, namely, good adherence to the substrate, andhigh durability for the compression involved in the molding operation.

It is to be appreciated that the coatings as applied may requiresubsequent processing steps such as buffing and polishing, grinding ormachining, and the like, as is well known in the art.

It is likewise to be appreciated that the post treatment of the thermalsprayed coatings can take a variety of steps such as sealers or othercorrosion protection. Preferably, however, a post treatment of heatingor fusion may be utilized as desired. Other post treatments couldinclude coating by impingement, electrolytic plating, electrolessplating, nitriding, anodizing, and the like.

FIG. 1 shows the mold 10 of the present invention. A metallic bodyportion 12 has a cavity portion 14. Shown is a cavity for a blow moldedbottle with a top portion 16. FIG. 1 is a perspective view of the mold,while FIG. 2 is a cross-section of the mold taken along lines 2--2 ofFIG. 1. The thermal spray is applied in a process that would permit ahigh volume such as a movable conveyor 18 which passes the mold 10within an appropriate distance from the gun 18. The gun has an inlet 20for powder particles to be inserted therein from a hopper (not shown). Afuel gas inlet 22 can be ignited, thereby warming the powder to themolten state. There is optionally also an oxygen inlet 24 to assist incombustion. Particles thereby are sprayed through outlet 26, whichparticles 28 are now in the molten form schematically shown as a sprayin FIG. 3. The mold 10, after the application of thermal spray, then hasthe cavity portion coated with the thermal spray coating 30. The outletportion of the gun 26 may have placed thereon a coating to facilitatethe movement of the particles through the outlet. This coating isgenerally a disulfide or a sulfide material of metallic character suchas titanium, molybdenum, tantalum, and the like. The coating isgenerally applied by chemical vapor deposition utilizing techniquesknown in the art.

After an appropriate pair of molds are formed, they are held together ina molding process such as a blow molding process, as shown in FIG. 4.This demonstrates that the process permits the formation of a blowmolded product such as a milk container 32, schematically shown in FIGS.4 and 5, where the molding occurs in FIG. 4, while FIG. 5 shows therelease of the blow molded product 32.

The mold of the present invention can be used for a variety of end uses.A preferred use is the application of the mold in the formation ofplastic products. The plastic that may be utilized is one that can beblow molded, injection molded, and other molding techniques. The moldingmay also include a RIM process (reaction injection molding). The plasticmaterials may be thermoplastic materials such as those that soften uponthe application of temperature and upon cooling conform to a new shape.A subsequent application of heat would allow the material to take on anew shape as desired. Thermoset materials are those that set withinapplication of temperature and/or pressure and/or catalysts to a fixedand firm position. A subsequent application of a heat does not permitdeformation, but rather destruction, of the bonds involved in theformation of the thermoset final product in the first place. Examples ofthermoplastic materials are polystyrene, acrylonitrile, styreneacrylonitrile, polyvinyl chloride (PVC), polyethylene terephthlate(PET), polysulfone, polyethylene, polypropylene, high density and lowdensity polyethylene materials, nylon materials, (polyamides), oxygenbarrier materials such as PET, PPOH, PVDC (polyvinyl dichloride),polytetrafluoroethylene (PTFE), polyvinylidene chloride, polypropylene,polybutylene, polyisobutylene, and the like. With respect to thermosetmaterials, such materials may be epoxy materials, polyurethanematerials, polyester materials, polyacetates, polycarbonates,poly(methyl)methacrylates, and the like. Also to be contemplated asplastic materials would be elastomeric such as rubber materials orsynthetic rubber materials, styrene butadiene, isopropylene, and thelike.

In general, if one utilizes the lightweight molds of the presentinvention for the thermal application of thermoset materials, thedesired characteristics of the tooling would be to have good heatcontrol, good heat transfer efficiency, wear resistance and chemicalresistance. The tools that would be utilized are thermal forming toolsor dies as well as injection molds. The materials that would preferablybe utilized are urethanes, such as flexible foams, rigid foams andsolids. Other materials would be epoxies; phenolics, such as novolacs;amines, such as polyamines; silicones, such as methochlorosilane;composites, such as engineering materials; thermoset polyesters andwood-containing materials; allyls, such as polyester resins derived fromesters of allyl alcohol and dibasic acids. Common monomers are allyldiglycol carbonate, also known as diethylene glycol bis (allylcarbonate), diallyl chlorendate, diallyl phthalate, diallyl isophthalateand diallyl maleate.

The present invention is likewise applicable towards the shaping,forming and molding of thermoplastics. In that situation, the toolingshould have the desired characteristics of having good thermal control,high-heat transfer efficiency, wear resistance as well as chemicalresistance. The tooling that would be utilized would generally be blowmolds, injection molds, as well as thermoform dies. The most preferredmaterials that would be formed are thermoplastic materials such aspolystyrenics; ABS (acrylonitrile/butadiene/styrene); SAN(styrene/acrylonitrile polymer); polyethylene; polypropylene;polycarbonates; polysulfones; polyethylene terephthalates; polyamidessuch as nylon and the like; glass materials and metals such as aluminum,aluminum alloys, zinc and zinc alloys, copper, copper alloys, tin andtin alloys.

Another distinct advantage of the present invention is that the body inwhich the cavity is sprayed thermally is formed of material that isreadily machined. Due to the ease of the machining of aluminum or wiremesh (or metal felt (fiber)) materials, a CAD/CAM device can be utilizedto simplify the manufacture of a mold. After one selects the end use ofthe mold, namely the product to be molded, one can machine the moldreasonably inexpensively and quickly with a CAD/CAM device. Due to thewide-open nature of the body of the mold, it is relatively easy tomachine to a desired configuration. In addition, due to the wide-opennature of the body of the mold, it is highly porous. The porosity wouldfacilitate cooling of the mold, thereby increasing cycle time formolding operations.

More broadly, the molds, dies and forming tools can be designed tooptimize the heat transfer efficiency for whatever part manufacturingtask is to be done. The rate limiting step to the manufacturing cyclenormally consists of the rate of heat flow through the plastics plus therate of heat flow from the mold. With the technology described herein,one can significantly decrease the heat flow contribution from the mold.Hence, the manufacturing cycle time for plastic part production can bedecreased significantly.

A wide variety of shapes can be molded. The appropriate configurationfor the mold can be designed utilizing a CAD CAM technique. Threedimensional datasets for a particular configuration can be obtained fromViewpoint Corporation's (of Oren, Utah) dataset catalog. The datasetcould be of a bottle, whether it be plastic or glass, or otherindustrial configuration such as beepers, telephone handsets, computerkeyboards, computer covers, gavels, guitars, and the like. Withutilization of such 3-D datasets, one can then configure the mold thatwould be used to form the final end product utilizing the techniques asdescribed herein for the convenient shaping of the mold itself.

Some particular uses of the molds for fabrication are described below.

One could use the molds of the present invention for the fabrication ofurethane foam parts for automotive seating. The desired moldcharacteristics would be that they would have an isothermal moldingsurface, moderate heat transfer efficiency, moderate compressionstrength, good release surface (renewable), long-wearing closuresurfaces, and be lightweight. The desired mold body would be comprisedof aluminum. The materials of construction for the mold body wouldpreferably be a screen or a foam or jack straws or a honeycombstructure, or the power-packing media as described above. The materialsof construction for the mold cavity would preferably be aluminum, oraluminum graphite spheres, or ultra high molecular weight polyethylene.For the latter technique, the high melting temperature polyethylenewould be stable at the foam formation temperature of the urethane, whichis generally 150°-200° F. The polyethylene is stable at that temperatureand the foamed urethane may be separated therefrom.

It is to be appreciated that the application of the ultra high molecularweight polyethylene will use commercially available equipment. It isusually different than that used for the application of metals. Suchequipment may be similar to that used in powder coating processes. Thepowder is generally applied by an air atomization process (charged orotherwise) directly onto a heated substrate which is then subjected to aheat curing process.

It should also be appreciated that a variety of high temperaturethermoset or thermoplastic powder materials may be coated. They may bepolyethylene, polypropylene, epoxies, polyamides as nylons,(meth)acrylics, polyphenylene sulfide, polysulfone, polybenzimidazole,and the like.

When a plastic powder material is used, the cavity is preferablypreviously formed by the thermal sprayed metallic particles as describedherein. This provides a smoother surface for the application of theplastic powder.

The molds of the present invention could also be used for thefabrication of plastic containers via blow molding. In that situation,the desired mold characteristics would be an isothermal molding surface,a high heat transfer efficiency, moderate compression strength for thecavity, high quality finish, lightweight, non-corroding surface finish,and a high compression strength for the mold closure surfaces. The bodymold would be comprised of aluminum. The materials of construction forthe lightweight portion of the mold body would be preferably a screen,or foam, or felt, or packing-tower media. The materials of constructionfor the mold cavity would preferably be aluminum with nickelelectroplated on top or aluminum with trinickel aluminide on top oraluminum with titanium nitride on top.

The tooling for fabrication of aluminum diecasting would be of a naturethat the mold or the die would have a high resistance to thermal cyclefatigue and thermal shock during mold filling and emptying. In otherwords, there would need to be high, hot strength and toughness as wellas having high thermal conductivity, that is, greater than about 100watts/meter--Kelvin, as well as have low coefficient of thermalexpansion. The tooling likewise would need to have high resistance ofthe materials of construction to erosion and wetting by the moltenaluminum. In other words, low solubility of materials of construction inmolten aluminum, high thermodynamic stability of the materials ofconstruction in relationship to molten aluminum, and lastly, have highmelting point for the materials of construction. The materials ofconstruction for the tool body preferably would becopper/dichromium-niobide, nickel or stainless steel, or nickelaluminide. The form of the materials of construction for the body of thetooling would be preferably foam, or screen, or felt, or tubing, orhoneycomb, or perforated sheet/plate, or sintered walls. The materialsof construction for the cavity membrane would preferably be nickelaluminide/nickel aluminide molybdenum/molybdenum; trinickelaluminide/trinickel aluminide-molybdenum/molybdenum; nickelaluminide/nickel aluminide-molybdenum/molybdenum; nickel/nickelmolybdenum/molybdenum; nickel/nickel-boron/nickel boron/trinickelaluminide; molybdenum; molybdenum/molybdenumboron/molybdenum boron. Withrespect to the details of construction for the mold, one should combinethe solid petitions and low density volumes as required. An inexpensivefiller may be used in the bottom of the mold. One can also use an openmatrix structure so as to enlarge the thermal sprayed membrane. One canalso use a structure which can be readily recycled and repaired.

As to the tooling for the fabrication of molten glass, the properties ofthe tooling should be such that they are resistant to thermal cyclefatigue and thermal shock. In other words, the tooling should havesuperior high strength and toughness as well as have low thermalcoefficient of thermal expansion and have an adequately high thermalconductivity (greater than 100 watts/meter--Kelvin). In addition, thetooling should have a high resistance to the corrosive action of moltedglass. The materials should have a high melting point, yet have lowsolubility of the materials of construction in molten glass. The toolingshould have surface modifications which permit a protective coating tothe working surface of the tools. The tooling should have highresistance to the oxidizing strength of molten glass yet have highthermal conductivity stability of the materials of construction tomolten glass. The tooling should have surface modifications which permitprotective coating to the working surface of the tools yet have a highwear-resistance to the wear of the working surface of the tool createdby the molten glass. The tooling should have a high hot hardness. Thetooling should have a high modulus at elevated temperatures, high glosssurface for aesthetics, and have a fine grain size via thermoplasmaspray coating of fine powders used for the materials of construction ofthe cavity membrane or coating.

The materials of construction for the tool body are preferably nickel,chromium/dichromium niobide, stainless steel, iron steel, graphite,nickel carbide, or nickel aluminide.

The form of materials of construction for the body itself preferablywould be a foam or a screen or sintered walls, or tubes or honeycombs,or felt.

The materials of construction for the cavity membrane may be as follows(multiple layers as indicated):

Ni--Al/Ni--Al--Mo/Mo

Ni3Al/Ni3Al--Mo/Mo

NiAl/NiAl--Mo/Mo

Ni/Ni--Mo/Mo

Ni/Ni--B/NiB

Ni3Al

Mo

Mo/Mo--B/MoB

The tooling for the fabrication of the molding compound-based parts areas follows. The tool characteristics should have an isothermal moldingsurface; 300° F. operating temperature; mar and wear-resistant surface;class A, super finish surface; 3-500 psi (minimum) compression strength;be lightweight and reasonably good heat transfer efficiency. Thematerials have of construction would be aluminum and stainless steelpreferably. The types of materials of construction for the tool bodywould be screen or packing-tower material, or jack straws, or honeycomb,or foam, or felt. The materials of construction for the tool formingsurfaces would preferably be aluminum/nickel aluminide oraluminum/electrolytic application of nickel, or stainless steel.

While the forms of the invention herein disclosed constitute presentlypreferred embodiments, many others are possible. It is not intendedherein to mention all of the possible equivalent forms or ramificationsof the invention. It is understood that the terms used herein are merelydescriptive rather than limiting and that various changes may be madewithout departing from the spirit or scope of the invention.

What is claimed is:
 1. A method of making a mold or die comprising thesteps of:a) providing a porous heat exchanging body support memberhaving a defined porosity; b) configuring a surface of the supportmember to a desired cavity; and c) thermal spraying particles to theconfigured cavity in the support member, thereby producing a mold ordie.
 2. The method of claim 1 wherein the sprayed particles aremetallic.
 3. The method of claim 1 wherein the sprayed particles areplastic.
 4. The method of claim 1 wherein the body is comprised of afoamed metal.
 5. The method of claim 4 wherein the foamed metal iscomprised of aluminum.
 6. The method of claim 1 wherein the body iscomprised of wire screen members having apertures for flow of coolanttherethrough.
 7. The method of claim 1 wherein the mold cavity has thestrength to form molded plastic pieces.
 8. The method of claim 1 whereinthe mold cavity has the strength to form molded metallic pieces.
 9. Themethod of claim 5 wherein the mold cavity has the strength to formmolded plastic pieces.
 10. The method of claim 5 wherein the mold cavityhas the strength to form molded metallic pieces.
 11. The method of claim1 wherein the body support member is porous metal.
 12. The method ofclaim 1 wherein the body support member is comprised of felt metal. 13.The method of claim 1 wherein the body support member is comprised offibrous metal.
 14. The method of claim 1 wherein the body support memberis comprised of metallic structured packing.
 15. The method of claim 1wherein the body support member is comprised of metallic tower-packing.16. The method of claim 1 wherein the body support member is comprisedof metallic Raschig rings.
 17. The method of claim 1 wherein the bodysupport member is comprised of corrugated wire gauze.